The present invention relates to a surgical system for providing an indication of media types and more particularly to a system for indicating the type of media in which a surgical instrument is disposed.
Anatomically, the eye is divided into two distinct parts—the anterior segment and the posterior segment. The anterior segment includes the lens and extends from the outermost layer of the cornea (the corneal endothelium) to the posterior of the lens capsule. The posterior segment includes the portion of the eye behind the lens capsule. The posterior segment extends from the anterior hyaloid face to the retina, with which the posterior hyaloid face of the vitreous body is in direct contact. The posterior segment is much larger than the anterior segment.
The posterior segment includes the vitreous body—a clear, colorless, gel-like substance. It makes up approximately two-thirds of the eye's volume, giving it form and shape before birth. It is composed of 1% collagen and sodium hyaluronate and 99% water. The anterior boundary of the vitreous body is the anterior hyaloid face, which touches the posterior capsule of the lens, while the posterior hyaloid face forms its posterior boundary, and is in contact with the retina. The vitreous body is not free-flowing like the aqueous humor and has normal anatomic attachment sites. One of these sites is the vitreous base, which is a 3-4 mm wide band that overlies the ora serrata. The optic nerve head, macula lutea, and vascular arcade are also sites of attachment. The vitreous body's major functions are to hold the retina in place, maintain the integrity and shape of the globe, absorb shock due to movement, and to give support for the lens posteriorly. In contrast to aqueous humor, the vitreous body is not continuously replaced. The vitreous body becomes more fluid with age in a process known as syneresis. Syneresis results in shrinkage of the vitreous body, which can exert pressure or traction on its normal attachment sites. If enough traction is applied, the vitreous body may pull itself from its retinal attachment and create a retinal tear or hole.
Various surgical procedures, called vitreo-retinal procedures, are commonly performed in the posterior segment of the eye. Vitreo-retinal procedures are appropriate to treat many serious conditions of the posterior segment. Vitreo-retinal procedures treat conditions such as age-related macular degeneration (AMD), diabetic retinopathy and diabetic vitreous hemorrhage, macular hole, retinal detachment, epiretinal membrane, CMV retinitis, and many other ophthalmic conditions.
A vitrectomy is a common part of a vitreo-retinal procedure. A vitrectomy, or surgical removal of the vitreous body, may be performed to clear blood and debris from the eye, to remove scar tissue, or to alleviate traction on the retina. Blood, inflammatory cells, debris, and scar tissue obscure light as it passes through the eye to the retina, resulting in blurred vision. The vitreous body is also removed if it is pulling or tugging the retina from its normal position. Some of the most common eye conditions that require a vitrectomy include complications from diabetic retinopathy such as retinal detachment or bleeding, macular hole, retinal detachment, pre-retinal membrane fibrosis, bleeding inside the eye (vitreous hemorrhage), injury or infection, and certain problems related to previous eye surgery.
A surgeon performs a vitrectomy with a microscope and special lenses designed to provide a clear image of the posterior segment. Several tiny incisions just a few millimeters in length are made on the sclera at the pars plana. The surgeon inserts microsurgical instruments through the incisions such as a fiber optic light source to illuminate inside the eye, an infusion line to maintain the eye's shape during surgery, and instruments to cut and remove the vitreous body.
The surgical machines used to perform procedures on the posterior segment of the eye are very complex. Typically, such ophthalmic surgical machines include a main console to which numerous different tools are attached. The main console provides power to and controls the operation of the attached tools. The attached tools typically include probes, scissors, forceps, illuminators, vitrectors, and infusion lines. A computer in the main surgical console monitors and controls the operation of these tools.
In a vitrectomy, for example, the vitrector cuts the vitreous body which is then removed through aspiration. An infusion line supplies intraocular irrigating solution to assist in the removal of the cut vitreous tissue. To remove vitreous effectively, a surgeon keeps the vitrector in the vitreous at the interface between the intraocular irrigating solution and the vitreous itself. If the vitrector is not kept in the vitreous, it does not effectively remove the vitreous. This can prolong surgery resulting in inefficiencies and possible detrimental effects to the patient. It would be desirable to know if a surgical instrument, such as a vitrector, is properly placed in the eye.